Feature Request: Display resource size usage in nomos vet validation

### Checklist

- [x] I did not find a related open enhancement request.
- [x] I understand that enhancement requests filed in the GitHub repository are by default low priority.
- [x] If this request is time-sensitive, I have submitted a corresponding issue with [GCP support](https://cloud.google.com/support-hub).

### Describe the feature

Description: Currently, the nomos vet command validates configurations but does not provide sufficient visibility into how close the resources are to hitting system limits (such as the ResourceGroup object size limit). Users have reported that the tool often doesn't give a clear indication of usage versus the limit, making it difficult to know when they are approaching a breaking point.

Feature request: Enhance nomos vet to calculate and display the estimated size of the resources being validated. The output should indicate how close the current configuration is to the maximum allowed limit (e.g., by showing the utilized percentage or total byte size), rather than just the number of objects.

Alternatives considered: Relying solely on object counts, which is often an inaccurate heuristic for the actual serialized size of the objects.

Similar issue https://github.com/GoogleContainerTools/config-sync/issues/2018

### Importance

_No response_